1. Field of the Invention
The present invention relates to an information terminal including cellular phones, PDAs, palm PCs and the like, and more particularly, to a hinge device of an information terminal for rotatably coupling a main body and a sub-body of the terminal.
2. Description of the Related Art
Mobile communication services, which have gradually developed from initial pager services, provide various data communications which include multi-media information as well as voice. In accordance with these developments, terminals for use in mobile communication services are developing into an information terminal form, which integrates functions of cellular phones, personal computers and multi-media appliances. Such information terminals are much leaner and lighter than existing devices, thereby maximizing portability.
In the case of cellular phones, for example, bar type terminals have been used mainly during their initial development stage. The bar type terminal is configured so that its single body housing is provided with receiver and transmitter modules, a display device and a keypad. The bar type terminals are limited in their miniaturization due to a required minimal distance between the receiver and transmitter modules. In order to solve the limitation in miniaturization of terminals, folder type terminals are used. Folder type terminals comprise a main body, a sub-body and a hinge device for rotatably coupling the main body with the sub body. The sub-body is configured to rotate, thereby being opened away from, and closed to, the main body. In a conversation mode, the sub-body of the folder type terminal rotates to be opened away from the main body, thereby ensuring a sufficient distance between transmitter and receiver modules of the terminal. In a call waiting mode, however, the sub-body of the terminal is folded to come into contact with the main body, resulting in an increase in portability. This configuration of the terminal using the hinge device is utilized for miniaturization of various information terminals, such as electronic notepads, notebook PCs and the like.
One example of a hinge device used in folder-type terminals is disclosed in U.S. Pat. No. 6,292,980 (the '980 patent), issued to Yi, et al., on Sep. 25, 2001, the entire contents of which are incorporated herein by reference. The disclosed hinge device disclosed in the '980 patent is designed to rotatably couple a main body and a sub-body of a terminal. If the user rotates the sub-body of the terminal to be opened away from the main body in excess of a predetermined angle, the hinge device provides a driving force allowing the sub-body to be forced toward its open position, without requiring any additional external force. If the user rotates the sub-body of the terminal below the predetermined angle, the hinge device provides a driving force for causing the sub-body to be forced to come into close contact with the main body.
However, disclosed conventional hinge devices discussed above still have shortcomings in that they are simply devices for opening and closing the sub-body of folder-type terminals. It is difficult to adjust an opening angle of the sub-body using the aforementioned hinge device, and therefore is inconvenient to use in that the user has to manually open and close the sub-body.